Replication of DNA 1.2

Question 1

What happens prior to cell division?

Answer 1

DNA is replicated by a DNA polymerase.

Question 2

What does DNA polymerase need to to start replication?

Answer 2

primers.

Question 3

What is a primer?

Answer 3

A primer is a short strand of nucleotides which binds to the 3’ end of the template DNA strand allowing polymerase to add DNA nucleotides

Question 4

What does DNA polymerase do?

Answer 4

adds DNA nucleotides, using complementary base pairing, to the deoxyribose (3’) end of the new DNA strand which is forming.

Question 5

What is the first step of DNA replication? 🧬

Answer 5

DNA is unwound and hydrogen bonds between bases are broken to form two template strands

Question 6

What is the second step of DNA replication? 🧬

Answer 6

A primer binds to the 3’ end of the template strand allowing polymerase to add DNA nucleotides.

Question 7

What is the third step of DNA replication? 🧬

Answer 7

Free DNA nucleotides in the cytoplasm enter the nucleus and join with their complementary base partners.

Question 8

What is the fourth step of DNA replication? 🧬

Answer 8

DNA polymerase adds DNA nucleotides, using complementary base pairing, to the deoxyribose 3’ end of the new DNA strand which is forming.

Question 9

What is the fifth step of DNA replication?🧬

Answer 9

New DNA molecules retwist into 2 identical DNA double helixes.

Question 10

What happens on the leading strand?

Answer 10

a primer binds to the DNA and polymerase adds free DNA nucleotides continuously in the 5’ to 3’ direction according to the complementary base pairing rule.

Question 11

What happens on the lagging strand?

Answer 11

a primer binds to the DNA once it is exposed and DNA polymerase adds DNA nucleotides to the 3’ end. As more DNA is exposed, a new primer is added. DNA polymerase extends the new strand from this primer until it meets the previous fragment.

Question 12

What joins the fragments on the lagging strand together?

Answer 12

Ligase.

Question 13

What is required for DNA replication?

Answer 13

DNA template, free DNA nucleotides, ATP, enzymes and primers.

Question 14

Why is DNA replication important?

Answer 14

Needed before cell division, makes up an organisms specific genotype, ensures that an exact copy of an organisms genetic information is passed on during cell division and required for normal cell function.

Question 15

What is polymerase chain reaction (PCR)?

Answer 15

amplification of DNA using complementary primers for specific target sequences.

Question 16

Why is PCR useful?

Answer 16

highly specific, easily automated and capable of amplifying minute quantity of sample.

Question 17

Uses of PCR in modern day life are…

Answer 17

..medicine, forensic science, genetic research and phylogenetics.

Question 18

What is required for PCR?

Answer 18

a DNA sample, primers, free DNA nucleotides, heat-tolerant DNA polymerase and energy.

Question 19

What process does PCR use?

Answer 19

Thermocycling, repeating cycles of heating and cooling.

Question 20

Describe the process of PCR.

Answer 20

DNA is heated to between 92 and 98°C to separate the strands. It is then cooled to between 50 and 65°C to allow primers to bind to target sequences. It is then heated to between 70 and 80°C for heat tolerant DNA polymerase to replicate the region of DNA.

Question 21

In PCR what are primers?

Answer 21

short strands of nucleotides which are complementary to specific target sequences at the two ends of the region of DNA to be amplified.